The invention relates to a power steering for a motor vehicle, having an input shaft which is rotatable about a steering axis, a steering column tube arranged around the input shaft, a sensor housing which is axially adjacent to the steering column tube and has a housing opening for the input shaft, and a shaft expansion element which is connected with the input shaft and has an outside diameter, the input shaft extending through the steering column tube and the housing opening into the interior of the sensor housing.
Power steering systems of this type are already known from the prior art and provide an auxiliary steering torque when required, which assists the driver in steering a motor vehicle. The input shaft is usually connected with an output shaft of the power steering by means of a torsion bar, the output shaft being, in turn, connected with steerable wheels of the motor vehicle by means of a steering gear.
Since in the case of a fracture of the torsion bar or of a torsion bar attachment a continued, reliable steering of the vehicle by means of the steering wheel must be ensured, design safeguard measures have already been proposed which make sure that in such cases a mechanical connection exists between the input shaft and the output shaft.
For example, variant embodiments are known in which a retaining ring is clipped into a groove formed on the input shaft and, further, a ring-shaped stop member is fastened in the steering column tube of the power steering, the inside diameter of the stop member being smaller than the outside diameter of the retaining ring. In this way, it is reliably prevented that the steering wheel, along with the input shaft fastened thereto, can be pulled axially out of the steering column tube and therefore the mechanical connection between the steering wheel and the steerable wheels of the motor vehicle is lost.
Since both the retaining ring and the stop member need to be manufactured as separate safety components and need to be reliably fastened to the input shaft and the steering column tube, respectively, this measure for safeguarding the axial position of the input shaft is time-consuming in terms of production engineering and assembly technology.